A large enantiornithine bird from the Lower Cretaceous of China and its implication for lung ventilation

Abstract

The Enantiornithes were the most taxonomically diverse bird group in the Mesozoic. Most of the known taxa are from Lower Cretaceous deposits of the Jehol Group in north-eastern China. A new specimen from the Jiufotang Formation in Jianchang, Liaoning Province, is described here; being a subadult individual at the time of death it had reached a relatively large size. The presence of uncinate processes, bicapitate and forked vertebral ribs, sternal ribs that were all of similar length, as well as the location of parapophyses and diapophyses on the thoracic vertebrae, may imply a rigid and volume-constant lung, and less efficient lung ventilation in enantiornithines.